Avoiding using globals in python

Question

How can I re-write this program to avoid using my global num1 and num2? I have an extra credit assignment in my programming class to rewrite a couple of programs without using globals, but this one has me stumped...

# Define the main function
def main():
    randomNumbers()
    print "Please add the following numbers:"
    print "  ", num1
    print "+ ", num2
    print "------"
    correctAnswer = num1 + num2 
    userAnswer = int(raw_input("   "))
    if userAnswer == correctAnswer:
        print "Great job!"
    else:
        # Return the correct answer for the user
        print "You're wrong! The correct answer was %s!" % correctAnswer 

# Define a function to generate random numbers
def randomNumbers():
    import random # Imports the random module

    # Generates two random numbers to be added
    global num1
    global num2
    num1 = random.randrange(100,1000)
    num2 = random.randrange(100,1000)

# Call the main function
main()

Got it figured out! Thank you so much!

# Define the main function
def main():
    num1, num2 = randomNumbers()
    print "Please add the following numbers:"
    print "  ", num1
    print "+ ", num2
    print "------"
    correctAnswer = num1 + num2 
    userAnswer = int(raw_input("   "))
    if userAnswer == correctAnswer:
        print "Great job!"
    else:
        # Return the correct answer for the user
        print "You're wrong! The correct answer was %s!" % correctAnswer 

# Define a function to generate random numbers
def randomNumbers():
    import random # Imports the random module
    rand1 = random.randrange(100,1000)
    rand2 = random.randrange(100,1000)
    return rand1, rand2

# Call the main function
main()

put the random calls in the main function and forget about the random function — Padraic Cunningham
– Padraic Cunningham, Commented Sep 25, 2014 at 23:17

recursive · Accepted Answer · 2014-09-25 23:26:51Z

3

If you make your randomNumbers() function return like this, you can avoid global state.

def main():
    # calculate something
    num1, num2 = randomNumbers()
    # calculate something else

def randomNumbers():
    # calculate something
    return num1, num2

Combining two values into one value this way is called a "tuple" if you want to look up more information or documentation.

edited Sep 25, 2014 at 23:26

answered Sep 25, 2014 at 23:18

recursive

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4 Comments

Michael Petch Over a year ago

I guess you get the extra credit for this assignment ;-)

Steven Pink Over a year ago

@recursive I understand that part... But I can't figure out how to print the return values and check them

recursive Over a year ago

@StevenPink: You print and check them exactly the same way you are now. There is no change at all.

Steven Pink Over a year ago

Thank you! It finally clicked for me :) I haven't used functions with more than one variable before

T.Woody · Accepted Answer · 2014-09-25 23:20:49Z

# Define the main function
def main():
    num1 = randomNumbers()
    num2 = randomNumbers()
    print "Please add the following numbers:"
    print "  ", num1
    print "+ ", num2
    print "------"
    correctAnswer = num1 + num2 
    userAnswer = int(raw_input("   "))
    if userAnswer == correctAnswer:
        print "Great job!"
    else:
        # Return the correct answer for the user
        print "You're wrong! The correct answer was %s!" % correctAnswer 

# Define a function to generate random numbers
def randomNumbers():
    import random # Imports the random module

    # Generates two random numbers to be added
    number = random.randrange(100,1000)
    return number


# Call the main function
main()

recursive · Accepted Answer · 2014-09-25 23:21:23Z

0

def main():
    num1 = random.randrange(100,1000)
    num2 = random.randrange(100,1000)
    print "Please add the following numbers:"
    print "  ", num1
    print "+ ", num2
    print "------"
    correctAnswer = num1 + num2 
    userAnswer = int(raw_input("   "))
    if userAnswer == correctAnswer:
        print "Great job!"
    else:
        # Return the correct answer for the user
        print "You're wrong! The correct answer was %s!" % correctAnswer

Try that?

edited Sep 25, 2014 at 23:21

recursive

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answered Sep 25, 2014 at 23:20

Nick

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1 Comment

Steven Pink Over a year ago

That would work, but we're supposed to use functions for computations like that when possible.

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